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Who doesn't love gears?  Gears let us transfer motion between all sorts of mechanisms.  The problem is, due to their precision operation, gears are seen as a fairly industrial solution to problems, and DIY'ers tend to stick with simpler things like chains and belts.

Gears are cool, and wanted to explore a little bit of what was out there, to help us make and use them.  Another advantage, is with the rising availability of precision CNC machinery to the home user, gears are even more plausible for us.

Involute Gears

There are many different types of gears, and gear-like mechanisms, out there:

• Cycloid gears
• Helical gears
• Involute gears
• Ratchets
• Splines
• Sprockets
• Spur gears
• Worm gears

Of most concern for someone designing a gear system is probably involute gears.  Involute gears are those whose teeth are shaped by a special design, called an involute curve.  The teeth mesh in a way that keeps them in constant contact, and produce a smooth, constant motion and velocity.

Personally, I had always sort of wondered where this gear tooth shape came from, and it turns out that the involute curve is the result of unwinding a string off of a center post.

Tools for Drawing Gears

So the next question, is "How do I draw gears, or design them, for my projects?"  There are tutorials on drawing them by hand, and computer tools for drawing them automagically.

• How to draw involute gear teeth
• Analytical Mechanics of Gears (Dover Science Books) (Paperback)
• Free online Gear Template Generator
• Gear Template Generator Program ($23)
• Generating Gears in Wood ($25)
• Gear-Wheel Designer with G-Code Output for CNC ($78)
• GearDXF makes DXF CAD files for gears
• Making Laser Cut Gears with [open-source] InkScape - may not be true involutes
• TrueGear AutoCAD addon - may be outdated

Uses of Gears

Well, the uses of gears are really up to you.  There are lots of great things people are doing out there with gears, and many are in wood are acrylic as hobbyist CNC is gaining ground.  Here are a couple examples:

• Kinekt Gear Ring Jewelry
• ;feature=player_embedded" target="_blank">Simple Rotational Casting Machine
• Wooden Gear Clock
• " target="_blank">Wooden Gear Window Blinds
• ;feature=related" target="_blank">Wooden "Nutty Device"